Uranium-cobalt alloy



Patented Nov. 13, 1951 U NI T E D URANIUM- COBALT ALLOY Application August 12, 1947, Serial No. 768,132

1 Claim. 1

The present invention is concerned with a binary uranium-base alloy and more particularly relates to a binary uranium-base alloy containing cobalt.

Uranium metal is extremely corrodible, oxidizes readily and may even ignite spontaneously when exposed to air at room temperature.

An object of the present invention is to improve the physical-metallurgical properties of uranium metal so as to enhance the corrosion resistance of uranium and to render the same useful for various purposes for which uranium metal heretofore has not been satisfactory.

Another object of this invention is to produce a binary uranium-cobalt alloy which is useful in the construction of neutronic reactors.

A further object of the invention is directed toward the formation of a new and novel composition of a binary uranium cobalt alloy to be used as an additive in the formation of more complex alloys containing uranium and cobalt.

Other objects of the present invention will be apparent from the following description taken with the accompanying drawing in which the single figure is a phase equilibrium diagram defining the uranium-cobalt system.

In accordance with the present invention the enhancement of chemical inertness of uranium metal is accomplished by the alloying effects of cobalt which tends toward decreasing corrosive attack by chemical reagents. In addition, by such alloying, uranium compositions are obtained in a form having a much lower melting point than uranium metal.

The present invention is concerned with new and novel compound of a binary uranium-cobalt alloy composition wherein the cobalt atomic per cent content is greater than 50 atomic per cent of the combined uranium-cobalt composition. Referring to the euuilibrium diagram, it was found that when preparing high cobalt content alloys of uranium, thermal analyses indicate that a uranium-cobalt compound, UCo2, having a cobalt atomic per cent of 66.6 was formed. This compound UCoz has a very high heat of fusion, for the liouidus breaks in the thermal data taken for this region were quite large and direct; and the microstructure of the alloys containing less than 66 per cent atomic cobalt showed an extremely dendritic phase structure. Beyond 66 atomic per cent cobalt a Widmansttten-like microstructure indicates a region of solid solubility of cobalt in UC02. In addition the X-ray diffraction patterns of the cuenched alloys substantially confirm this result. Uranium-cobalt alloys whose composition lies beyond the solubility limit of cobalt in UCoz contain a very typical eutectic structure. This eutectic was found to contain 8'7 atomic per cent cobalt and to melt at 1063 C.

The compound UCoz was identified by X-ray analysis to have a face-centered cubic structure, wherein the parameter, a, was equal to 6378310.004 The density of Uocz was found to be 13.83 grams per cubic centimeter.

The alloy of the present invention was prepared from uranium metal havin-g a purity greater than 99.9 per cent and of cobalt metal of 99.9 per cent purity. The metals were melted together in beryllia crucibles in vacuo by means of induction heating. Each alloy mass, weighing about 250-450 grams, was held at about 1500 C. for 20 minutes to allow the melt to come to equilibrium. Thermal data were taken by remelting the alloys and cooling at rates of about 6 to 7 C. per minute in the range of about 1000 C. with correspondingly lower rates at lower temperatures.

The alloy was prepared for microscopic examination by mechanical polishing techniques and electrolytic polishing using a phosphoric acidethylene glycol-ethyl alcohol solution.

All of the alloys above described in addition to the physical-metallurgical advantages, exhibit resistance to corrosion far superior to that of uranium metal.

Related compounds and compositions of uranium cobalt alloys which exhibit resistance to corrosion far superior than that of uranium metal have been described ln our co-pending application, Serial No. 770,624, led August 26, 1947.

It will be understood that the particular alloy compositions described above should not be deemed to constitute the limits of the invention. The scope of the invention is defined in the appended claim.

What is claimed is:

A composition of matter consisting of an intermetallic compound dened by the formula UCOz.

ADRIAN H. DAANE. WILLIAM K. NOYCE.

REFERENCES CITED The followingr references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 811,859 Marsh Feb. 6, 1906 FOREIGN PATENTS Number Country Date 158,508 Austria Apr. 25, 1940 OTHER REFERENCES Friend: Textbook of Inorganic Chemistry, vol. VII. part III, p. 286 (1926). Published by Charles Griffin and Co., Ltd., London.

Hansen: Aufbau der Zweistoiliegierungen, 1936, pages 515 and 959. 

